Stoker



July 13, 1937. w. R. mop I 2,086,760-

STOKER Filed Deo. 5, 193s 5 sheets-sheet 2 OOO `////// INVENTOR W` BY +Mw ATTORNEY$ W. R. WOOD July 13, 1937.

sToKER Filed Dec. 5, -1933 5 Sheets-Sheet 5 W. R, WOOD July 13,

STOKER 5 $heets sheet 4 I Filed De@ 5, 1955 By 7M ATTORNEYJ W. R. WOOD July 13, 1937.

STOKER Filed DGO. 5, 195:5

5 Sheets-Sheet 5 INVENTOR. f/ 6 MWL By W ATTORNEYf Patented July 13, 1937 UNITED STATES STOKER Wilfred Rothery to Combustion Wood,

Engineering Company, New York, N. Y., a cor New York, N. Y., assigner Inc., poration of Delaware Application December 5, 1933, Serial No. 700,946 15 claims. (o1. 122-376) This invention relates to fluid cooled stokers.

Suchstokershave been heretofore proposed and vthe general purpose of the present invention is to provide an effective stoker of this type which is capable of being operated at high rates, and, if desired, with the use of highly pre-heated combustion air.

There is a limit of rating at which mechanical stokers can be operated, particularly with pre-- heated combustion air, because of the temperature to which the Stoker parts in proximity to the burning fuel may be safely raised. Beyond such temperature, warping and burning out of certain of the parts occur. Hence, more specifically, it is an object of the invention to provide a simple and effective arrangement of the cooling parts, whereby not only warping and burning out of the stoker parts proper, but also warping and burning out of the cooling parts themselves, are avoided.

Another object of the invention is to correlate the cooling parts with the fuel supporting and fuel ^advancing parts of the stoker so that all of the parts co-operate to produce a Stoker which is simple in construction; has long life; is not liable to get out of order; and in which sifting through of riddlings is greatly minimized.

I also aim to provide an arrangement in which expansion and contraction of the parts `is provided for.

Still another object of the invention is to provide a circulation for the cooling parts which is effective in accomplishing the foregoing ends.

Other objects have to do with certain mechanical features and combinations of, parts, as will hereinafter appear.

How the foregoing together with suchv other objects and advantages as may hereinafter appear or are incident to my invention, are realized is illustrated in preferred form in the accompanying drawings, Wherein:-

uFigl is a vertical section throughua boiler and furnace installation embodying a stoker constructed in accordance with my invention; v

Fig. 2 is a fragmentary vertical cross section taken substantially on the line 2--2 of Figure l;

Fig. 3 is a fragmentary vertical cross section taken substantially on the line 3;-3 of Figure 1;

Fig. 4 is a plan'section taken substantially on the line 4-4 of Figure 1, with a porton of the fuel hopper appearing in full plan view;

Fig. 5 is an enlarged fragmentary longitudinal section taken substantially on the line 5-5 of Figure 4;

Fig. 6 is a fragmentary plan view of Figure 5;

Fig. '1 is a fragmentary cross section on the line 'l-l of Figure 1;

Figs. 8 and 9 are fragmentary cross sections taken on the lines B-B and 9--9 respectively, of Figure 5;

Fig; 10 is a longitudinal section similar to Figure 5, but showing a modification of the invention;

Fig. llis a cross section taken on Vthe line Ii-ll of Figure 10;

Fig. 12 is a cross section similar to Figure 11, but showing another modification of the invention; .A

Fig. 13 is afragmentary longitudinal view similar to Figure 5 and showing a further modiiication of the invention with one of the grate bars or pusher elements shown in section;

Fig. 14 is a fragmentary plan view of Figure 13;

Fig. .15 is a. longitudinal view similar to Figures 5 and 10but illustrating another modification of the invention; v

Fig. 16 is a cross section taken on the line lE--IG of Figure Fig. 17 illustrates a cooling tube detail;

Fig. 18 is a fragmentary View illustrating a dump grate at the ash discharge end of the Stoker and also an arrangement of cooling tubes for the ash pit; r A l Fig. 19 is a diagrammatic view showing a modified arrangement of f uel feed.

Referring more particularly to Figures 1 to 9 inclusive, my improved stoker `A is shown applied to a furnace B with which a boiler C-is associated, the boiler comprising in this instance, a main bank of inclined boiler tubes 23 connected at their lower ends into a downtake header' 24 and at their upper ends into an uptake header 25, an upper steam Aand water drum 26 .and a plurality of tubes 21 leading from the header 25 to the steam and water. drum 26.

In the furnace arrangement shown in Figure 1, steamgevaporating .tubes 28 Aand 29 are arrangedat the front and rear walls 3U and 3l respectively and similar steam evaporating tubes may be employed at the side walls. Water is led to the steam evaporating tubes -29 by means. of downcomer tubes 32 leading from the water spaceiof the steam and Water drum 26 to a lower header 33, into which the lower ends of the tubes 29 are connected. Thetubes 29 are connected at their upper ends into an upper header 34 from which upcomer tubes 35 and 36 lead to the steam space of the 'steam and water drum 26. The tubes 28` at the front wall of the furnace are connected at their lower ends intov a header 31 to which waterv is led in a manner hereinafter appearing and are connected at their upper ends l .of rods 56, blocks rams, driving mechanism 44 for reciprocating the rams, a plurality of feed openings 45 in the front wall 38 of the furnace through which fuel is fed by the rams to the grate surface of the stoker, and mechanism 46 for reciprocating the grate bars 48 to elect feed of fuel from front to rear of the grate.

'I'he cooling tubes 4| are arranged longitudinally of the grate in the direction of fuel feed and are inclined downwardly from front to rear, and at the rear or ash discharge end of the grate, these tubes are further bent downwardly so as to provide a water cooled front wall for the ash pit 41.

"I'he tubes 4| are connected at their lower ends into a lower header 48 to which water is led from the steam and water drum 26 by means of downcomer `tubes 32a, and are connected at their upper ends into the lower header 31 of the front wall tubes 28. It will thus be seen that circulation is from the drum 26 downwardly through the tubes 32a, then upwardly through the cooling tubes 4| to the header 31, and from thence upwardly through the wall tubes 28 and finally to the steam space of the drum 26 through the medium of the upper header 38 and upcomers 39, and since the tubes 28 are vertically disposed and subject to high heat, very effective circulation through the cooling tubes 4| in ensured.

'I'he cooling tubes 4| are spaced apart transversely of the grate and are provided with extended surfaces illustrated in Figures 1 to 9 in the form of lateral flanges 49 extending longitudinally of the tubes. These flanges may be Welded to the tubes so as to be in thermal contact therewith.

'Ihe grate bars 48 are positioned between the spaced cooling tubes and are arranged to ride on the anges 49, whereby any wear incident to movement of the grate bars is taken by the flanges, it being noted that the adjacent anges of adjacent tubes substantially abut one another and act to absorb heat from the moving stoker parts and transmit it to the cooling elements or tubes.

The grate bars are provided with downwardly extending plate-like l portions or lugs 58 passing through elongated slots 5| in adjacent flanges 49, and adjustably connected by means of pin and slot vconnections 52 to bars 53 located below the cooling tubes 4| and extending parallel thereto. In this instance, I have illustrated three longitudinally spacedgrate bars 48, between each pair of cooling tubes, as clearly shown in Figures 1 and 4. Each such row of grate bars is connected to a bar 53 and the bars 53 are connected in groups of three to an actuating rod 54 by means of a cross head 55, as clearly shown in Figures 1, 2, and 5. The actuating rods and their connected grate members have reciprocatory motion imparted thereto from the feeder rams 42, to which connection is made by means 51 and links 58 which parts constitute the mechanism 46 above referred to. Connection between the rods 56 and the rams 42 is made by means of downwardly projecting lugs 59 provided on the rams 42, collars 68, and adjusting nuts 6| provided on the rods 56` 'I'he nuts 6| may be adjusted to alter the strokes imparted to the grate bars.

Referring to Figure 4, it will be seen that in the particular stoker illustrated, live feeder rams are provided and that the grate bars are arranged in ve transverse groups, each composed of three sets of three grate bars. 'Ihe driving cranks of alternate rams are offset and since each group of nine grate bars is connected to a different ram, they will be positioned in staggered relation, as shown in Figure 4. The stroke of any group of grate bars may be altered by adjusting the adjusting nut 6| of its reciprocating mechanism 46. The arrangement thus provided is one whereby the coal is fed uniformly across the width of the stoker with the result that a uniform fuel bed is maintained and unequal lanes of firing avoided.

'Ihe grate bars 48 illustrated in Figures 1 to 9 are in the form of units made up of a base member 62 having a perforated nose 63 at its lower end, and five removable sections 62a to 62e, each provided with air ports 64. Each removable section is provided with a lip 65 which hooks under the top surface of the adjacent section and the upper section 62e is secured to the lower section 62 by means of a key and locking pin 66 associated with a depending lug on the section 62e and upstanding lugs on the base portion 61 of the main section 62. 'Ihus all of the parts referred to are secured together in a single unit or grate bar. Displacement of the grate bars in an upward direction is prevented by means of clips 62f secured to the depending lug 58 and co-operating With the flanges 49 of the cooling tubes.

In Figures 8 and 9 cross sections through the cooling tubes 4| and grate elements 48 are shown, it being noted that air passes from beneath the cooling tubes up between the adjacent flanges 49 into the interior hollow portion of the grate bars and out sideways through the air ports in the bars and into the fuel bed. The sides of the grate bars are preferably shaped to conform to the curvature of the tubes 4| whereby extended top grate surfaces are provided. These views clearly illustrate how the cooling elements and the bars provide the grate surface and also how any Wear caused by movement of the grate bars yrelative to the xed or stationary cooling elcments is taken by the extended surfaces or flanges 49 which are in thermal contact with the tubes. The arrangement of the cooling tubes, the extended surfaces and the grate members is such that the riddlings are conveyed along the grate by the movement imparted to the pushers thus avoiding the sifting of riddlings through the grate.

Provision for expansion and contraction may be made by anchoring the cooling tubes at the point from which expansion is to take place and by supporting them at other points with freedom to move when expansion and contraction occurs.

, In the particular embodiment shown in the drawings, the cooling tubes 4| are, anchored at the ash discharge end of the grate to the transverse supporting girder 68 by means of downwardly extending lugs 69 secured to the tubes and which are bolted to members 18 carried by the girder 68. Thus the tubes are free to expand longitudinally toward the forward or front end of the stoker. At this end the header 31 is seated in shoes 1| adapted to slide in guides 12 carried by the supporting girder 13. The shoe surfaces of the shoes and the corresponding surfaces of the guides 12 are inclined in the direction of expansion. At intermediate points additional support for the grate with freedom of expansion may be provided by means of intermediate girders 14 and similar shoe devices 15. The tubes 28 at the front wall of the furnace are spaced away from the wall to permit the grate.

lower header to shift as expansion of the cooling tubes 4I occurs. The wall tubes 28 expand upwardly for which purpose an expansion seal is provided where they pass through the wall. Expansion into the ash pit 41 occurs from the anchorage at the rear girder 68 downwardiy, the lower header 48 being free to. move in space and the downcomer tubes 32a being bent to enable such expansion. In some instances it may be desirable to provide the anchorage at the header 31 so that the expansion will be downwardly.

Transverse expansion is taken care of by clear-v ance betwen elements which, however, because of the arrangement, does not result in the sifting through of riddlings.

Referring now to Figures 1 and 2 the wall tubes 28 which act as risers for the cooling tubes of the grate are spaced apart suiiiciently to permit of fuel feed in between them and onto the However, in order to protect a greater furnace wall area by cooling surface above the fuel feed openings, these tubes 28 are bifurcated or divided into a plurality of tubes as shown at 16 in Figure 2 to provide closer ,tube spacing above the feed openings.

At the sides of the grate side wall cooling surface may be provided by means of tubes 11 equipped in this instance with heat absorbing blocks 18 (see Fig. '7). The adjacent tubes lli may also be equipped with similar blocks 19 to complete the corner.

An air casing 8U is provided beneath the grate to which pre-heated air for combustion may be led through a damper controlled inlet 8l and V from which pre-heated air may be led tol the fuel bed through a plurality of inner casings 82 each provided with an individually controllable damper-83. Air mayf alsol be led from'the casing 88 to'the ash pit casing Bil through a damper controlled opening 85 and from thence to the ash pit either through spaces between the flangesl 49 or through-slots therein. The air so admitted cools the ash and causes more complete burning out of combustibles remaining in the ash.

Air is admitted above the fuel bed through a plurality of air openings 86 directed toward the fuel bed and to which pre-heated air is led from the casing 80 by means of a damper controlled conduit 81. Additional air may be admitted with the fuel through openings 88.

In Figures 10 and 11 I have illustrated a modifled grate bar 40a. of one piece construction and provided with a depending lug 50a for connection to its actuator and having sidwir openings Gila. In Figure 11 the sides of the grate bar 40a are in close proximity to the cooling surface, and the air is admitted to the fuel bed through the spaces between the bar and cooling surfaces. This close proximity shields the lowergrate bars from the radiant heat of the fuel bed and subjects them to the radiant absorption of the cooled surfaces.

In Figure 412 I have illustrated still another modified form of grate bar 40h provided with a depending flange 40e which aids in cooling its top surface. In this instance the flanges or fins @9a on which the grate bars llb slide are welded to the bottom of the cooling tubes lll and the space between adjacent fins of adjacent tubes is such with respect to the thickness of the depending flange 60o that air may enter through spaces @0d and air openings 80e to the fuel bed, the arrangement being such that riddlings and siftings'are prevented from passing downwardly.

In the modification illustrated in Figures 13 and 14 the cooling tubes M are inclined in a manner similar to that described in connection with Figure 1, but the grate bars or pushers 89 are horizontally disposed and ride on horizontal flanges 90 secured to the tubes 4I. as by means of welding, and spaced longitudinally of the tubes. Reciprocatory movement is imparted to the grate bars by means of ram operated rods 9| and links 92. The front portions of the grate bars are of stepped formation and although the bars are horizontallyk disposed the grate surface presented thereby is generally inclined. In this form air is admitted to the fuel bed through openings 93 in the grate bars.

In Figure 19 I have shown a diagrammatic arrangement in which the uppermost group of pushers ill are aligned and tied together across the full stoker width and reciprocated by a common drive such las cranks |26 and connecting rods |21. With this arrangement the fuel is fed longitudinally and uniformly across the width of the Stoker, thereby avoiding lanes of uneven fuel feed. A multiplicity of small reciprocating rams" H28 may be employed to feed fuel to the pushersv illa.

In Figures l5 and 16 an arrangement is illustrated in which the ns il@ are spaced suiciently apart to permit the depending connecting lugs such as shown at Eil in Figure 5, to pass therebetween. In this case the grate bars are provided with extended ends E29 and i3@ adapted s to overlap and cover the openings between the fins at the points where the grate bars are spaced apart and thus prevent slftngs from falling through. This construction also permits of a wider spacing of the cooling elements and enables wider grate bars to be employed. If desired, sev- `eral grate bars may be attached together by employing securing means at the extensions 129 and In Figure 17, I have shown clips H38 alternately welded to the iin i3d of one cooling tube and` to the fm l35 of the adjacent cooling tube arranged to interlock when the tubes are assembled in the stoker, whereby alignment is provided.

In Figure 18 the ash pit 41 is equipped with a dump grate E36. The rear wall tubes 29 of the furnace and the grate cooling tubes lli are fed from common downcomers l31 which lead from the water space of the boiler.

I claim:

1. A water cooled Agrate comprising alternate cooling members and movable members to be cooled thereby, said cooling members being provided with lateral extended surfaces on which the movable members are Isupported and being spaced apart an amount leaving a space between the adjacent extended surfaces of adjacent cool-4 ing members, said movable members being arranged in groups spaced apart lengthwise of the grate, and means between said groups for covering the aforesaid space between the adjacent extended surfaces.

bination of movable grate bars, water tubes sloping downwardly from the front of the grate to the rear thereof, and horizontally disposed members in thermal contact with the tubes in spaced relation along the length of the tubes for supporting said grate bars in groups stepping downwardly from front to rear of the grate.

4.111 a water cooled grate for stokers, the combination of spaced coolingntubes having lateral extensions thereon, the adjacent extensions of adjacent tubes being spaced apart, and movable grate bars located between said tubes and supported on said extensions, said grate bars having depending flanges passing through the spaces between adjacent extensions of adjacent tubes.

5. Ina water cooled grate for overfeed stokers, the combination of spaced cooling tubes having longitudinally extending lateral flanges, reciprocatory grate members associated with said tubes, meansfor actuating said grate members, means extending downwardly from the grate members for connecting them to said actuating means, said flanges being slotted at intervals along their length to accommodate said downwardly extending means and substantially closing the spaces between the tubes for the remainder of their length.

6. In a water cooled grate for overfeed stokers, the combination of spaced cooling tubes having lateral extensions thereon, the adjacent extensions of adjacent tubes being spacedapart, and movable gra-te bars supported from the tubes at the spaces therebetween, said grate bars having depending flanges passing through the spaces between adjacent extensions of adjacent tubes.

7. A water lcooled grate comprising alternate cooling members and movable members to be cooled thereby, lateral extensions on said cooling members on which the movable members are supported, the adjacent lateral extensions of adjacent cooling members being arranged to approximately abut, said movable members being arranged for reciprocation in a direction lengthwise of the grate, and said lateral extensions due to their approximate abutting relation minimizing the passage of riddlings through the grate and preventing fuel from falling through the grate as the movable members reciprocate.

8. A water cooled grate comprising alternate cooling members and movable members to be cooled thereby, lateral extensions on said cooling members on which the movable members are supported, the adjacent lateral extensions of adjacent cooling members being arranged to approximately abut, and said movable members being arranged in groups spaced apart lengthwise of the grate.

9. A water cooled grate for stokers comprising laterally spaced inclined cooling tubes extending longitudinally of the grate; means in thermal contact with the tubes substantially closing the spaces between tubes; and reciprocating grate bars at the spaces between cooling tubes arranged in groups spaced apart lengthwise of the grate, said grate bars together with portions of said cooling tubes and said thermally contacting means combining to provide a complete luel supporting surface for the grate.

l0. A water cooled grate for stokers comprising laterally spaced cooling tubes extending longitudinally of the grate and provided with laterally extended surfaces of such extent that adjacent extended surfaces of adjacent cooling tubes approximately abut, and movable grate members associated with said tubes at said extended surfaces arranged in groups spaced apart lengthwise of the grate, said cooling tubes and their laterally extended approximately abutting surfaces constituting fuel supporting surface for the grate where such surface is not provided by the grate members.

1l. A water cooled grate for stokers comprising laterally spaced cooling tubes extending longitudinally of the grate and provided with laterally extended surfaces of suc-h extent that adjacent extended surfaces of adjacent cooling tubes approximately abut, and movable grate members associated with said tubes at said extended surfaces arranged'in groups spaced apart lengthwise of the grate, said movable grate members having openings therein for the admission of air to the fuel bed.

12. A water cooled grate for stokers comprising laterally spaced cooling tubes extending longitudinally of the grate and provided with laterally extended surfaces of such extent that adjacent extended surfaces of adjacent cooling tubes approximately abut, and movable grate members associated with said tubes at said extended surfaces arranged in groups spaced apart lengthwise of the grate, said movable grate members being of hollow form with closed tops and having openings in walls thereof for the passage of air to the fuel bed.

13. A water cooled grate for stokers comprising inclined laterally spaced water tubes extending downwardly from front to rear of the grate and spaced apart crosswise of the grate, grate members movable to effect downward feeding of fuel over the grate, and lateral extensions on said tubes of such lateral extent that the adjacent extensions of adjacent tubes approximately abut, said grate members being arranged in groups spaced apart longitudinally of the grate and being in overlapping relation to the adjacent extensions of adjacent tubes.

14. A Water cooled grate for stokers comprising inclined laterally spaced water tubes extending downwardly from front to rear of the grate and spaced apart crosswise of the grate, lateral extensions on said tubes of such lateral extent that the adjacent extensions of adjacent tubes approximately abut, grate members supported on the adjacent extensions of adjacent tubes in overlapping relation thereto, and means for reciprocating said grate members in a direction lengthwise of the grate, said lateral extensions constituting fuel supporting surface for the grate where such surface is not provided by the grate members, whereby fuel is prevented from falling through the grate as the grate members reciprocate.

15. A water cooled grate comprising alternate cooling tubes and movable grate bars to be cooled thereby, lateral extensions on said cooling members on which the movable members are supported, the adjacent lateral extensions of adja-` cent cooling members being arranged to approximately abut, and an ash pit, said cooling tubes and the lateral extensions thereof being extended downwardly into the ash pit to form a cooled wall therefor, and said lateral extensions due to their approximate abutting relation preventing excessive flow of air from the ash pit.

WILFRED ROTHERY WOOD. 

